What is the equation of the line perpendicular to $y=\frac{1}{2} x+3$ passing through the point $(-3,4)$ ?

A$y=\frac{1}{3} x+5$

B$y=\frac{1}{2} x+\frac{11}{2}$

C$y=-2 x+3$

D$y=-2 x-2$